I wouldn't doubt it and I guess that's the stock answer. The party line from 5Star is also that a fresh solution of Star San should be made for each sanitation run. However if you listen to the interview with Charlie Tally he gives the real answer.
It had not struck me before but I am coming to the end of a 16oz bottle of Star San which I bought in 2014. So it's 7 years old, still hits the required pH, foams like day 1 and the diluted solution made with deionised water is clear and remains so. Do I believe the 1 year lifetime? No, of course not. The bottle is kept in a dark cool cupboard as strong sunlight can degrade chemical compounds, but I can see no evidence whatsoever of any change after this length of time.